One mobile communication network element is a base transceiver station (also referred to as base station or NodeB or eNodeB) that typically contains radio frequency transmitters and receivers used to communicate directly with mobile radio communication terminal devices, such as mobile telephones, that move freely within a communication range of one or more such base stations. A type of base station, known as a femtocell may soon be added to many mobile radio communication networks.
A femtocell may be understood to be a modified base station for use in buildings or home environments in order to increase or improve the in-building coverage of the network. A typical use for such a femtocell may be, for example, in the home or apartment of a mobile radio communication terminal device user. The user would use a broadband (possibly wired) network connection, such as a conventional digital subscriber line (DSL) connection, to connect a femtocell to the user's mobile radio operator's core network. This usage may be beneficial for both the user and the mobile radio communication network operator, since the user may save money and battery power on his mobile radio communication terminal device due to improved coverage within his home or building, and the operator may receive additional network coverage and save on energy costs.
Mobile radio communication terminal devices may perform a “random access procedure” in order to establish a wireless connection with a base station or femtocell. A mobile radio communication terminal device may randomly select a mobile radio resource for transmission from a predefined set of mobile radio resources. A mobile radio resource may be, for example, a certain time slot at a certain radio frequency with a certain code. This access scheme is subject to collisions as a requesting mobile radio communication terminal device may request the same mobile radio resources already selected by another mobile radio communication terminal device. Collisions are undesirable because they waste mobile radio resources and increase transmission delays. To keep the collisions at an acceptable level, the amount of reserved mobile radio resources are conventionally aligned with the number of expected random accesses for each mobile radio cell. If the amount of reserved mobile radio resources is too large, the system performance wastes unused mobile radio resources. Therefore, it is important to properly balance reserved mobile radio resources with the anticipated traffic of a wireless mobile radio communication network cell.